.TH std::unexpected_handler 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::unexpected_handler \- std::unexpected_handler

.SH Synopsis
   Defined in header <exception>
   typedef void (*unexpected_handler)();  (deprecated in C++11)
                                          (removed in C++17)

   std::unexpected_handler is the function pointer type (pointer to function that takes
   no arguments and returns void), which is installed and queried by the functions
   std::set_unexpected and std::get_unexpected and called by std::unexpected.

   The C++ implementation provides a default std::unexpected_handler function, which
   calls std::terminate(). If the null pointer value is installed (by means of
   std::set_unexpected), the implementation may restore the default handler instead.

   A user-defined std::unexpected_handler is expected to either terminate the program
   or throw an exception. If it throws an exception, one of the following three
   situations may be encountered:

   1) the exception thrown by std::unexpected_handler satisfies the dynamic exception
   specification that was violated earlier. The new exception is allowed to escape the
   function and stack unwinding continues.

   2) the exception thrown by std::unexpected_handler still violates the exception
   specification:

   2a) however, the exception specification allows std::bad_exception: the thrown
   exception object is destroyed, and std::bad_exception is constructed by the C++
   runtime and thrown instead.

   2b) the exception specification does not allow std::bad_exception: std::terminate()
   is called.

.SH See also

   unexpected                function called when dynamic exception specification is
   (removed in C++17)        violated
                             \fI(function)\fP
   set_unexpected            changes the function to be called by std::unexpected
   (removed in C++17)        \fI(function)\fP
   get_unexpected            obtains the current unexpected_handler
   \fI(C++11)\fP(removed in C++17) \fI(function)\fP
